The bottleneck of many systems and their applications is located at the I/O level. Applications are demanding more and more speed and bandwidth from their data storage products. In addition to speed, an application such as Video on Demand (VOD), needs its disk accesses to be timely both in terms of speed and interval. That is, the requirement for VOD is that of high bandwidth without interruption. Specifically, the speed required for VOD must be sustained without interruption--resulting in uninterrupted movie clips.
Disk array systems have been developed to provide high availability and reliability. In particular, systems known as Redundant Array of Inexpensive Disks (RAID) provide resilience to disk failure through the use of multiple disks and data distribution and correction techniques. Unfortunately, the techniques for increasing reliability often result in slowing down an I/O operation.
It is desirable to devise systems and techniques for maintaining the reliability of RAID systems and at the same time increasing their speed.